Dropbox said the outage arose from routine maintenance. “We are aware of an issue currently affecting the Dropbox site,” the company said in an email. “We have identified the cause, which was the result of an issue that arose during routine internal maintenance, and are working to fix this as soon as possible. We apologize for any inconvenience.”

Just before 6 p.m. Pacific time, Dropbox tweeted that it was aware of the problems. Service was restored shortly after 8:30 p.m.

Dropbox said the outage was not work of hacking groups. According to separate tweets, the hacking collective Anonymous, through the Twitter account AnonKorea, and 1775 Sec, claimed responsibility for the outage. Dropbox said the claims were “a hoax.”